StatisticsDisplay.java

public class StatisticsDisplay implements Observer {
    private float maxTemperature = Float.MIN_VALUE;
    private float minTemperature = Float.MAX_VALUE;
    private float sumTemperature = 0;
    private int numReadings = 0;

    public StatisticsDisplay(Subject weatherData) {
        weatherData.registerObserver(this);
    }

    @Override
    public void update(float temperature, float humidity, float pressure) {
        sumTemperature += temperature;
        numReadings++;

        if (temperature > maxTemperature) {
            maxTemperature = temperature;
        }

        if (temperature < minTemperature) {
            minTemperature = temperature;
        }

        display();
    }

    public void display() {
        System.out.println("Avg/Max/Min temperature = " + (sumTemperature / numReadings) +
                "/" + maxTemperature + "/" + minTemperature);
    }
}